Stripper shredder for frangible sabots



United States Patent [72] Inventor Irwin R. Barr Lutherville, Maryland 1211 Appl. No. 801.243 {22] Filed Feb. 1-1. 1969 [-15] Patented Oct. 13.1970 [73] Assignee AAl Corporation,

Cockeysville. Maryland a corporation of Maryland Continuation of Ser. No. 606.387. Dec. 30. 1966 [54} STRIPPER SHREDDER FOR FRANGIBLE SABOTS 9 Claims. 5 Drawing Figs.

[52] U.S.Cl 89/14 {51] lnt.Cl ..F-t1c 21/18. F411 1 7/12 [50] Field of Search 89/ 1-1. l-HSBl: 42/78. 79: l02/93.94

[56] References Cited UNITED STATES PATENTS 868.938 10/1907 Puff 89/l-l(SB)UX Nelson 89/l4(.3)UX

2.115.028 4/1938 Logan lUl93X 2.811.901 11/1957 Barr 89/141SBlLX .212.208 10/1965 Persechino et a] 89 l-lISB/L'X FORElGN PATENTS 64.838 11/1892 German 42175 353.816 10/1937 Italy 411 b Primary Examinei-Benjamin A. Borchelt Assistan! E.raminer-Stephen C. Bentley Anurney-Reginald F. Pippin. Jr.

ABSTRACT: A stripper-shredder arrangement on a smooth bored gun for launching a projectile through the medium 01a sabot which is stripped from the projectile and shredded lntu fine pieces by the stripper-shredder at the end of the barrel. the pieces being laterally ejected through openings in the stripper-shredder beyond the stripper section and adjacent the shredder section.

Patented Oct. 13, 1970 Sheet nmm Patented Oct. 13, 1970 Sheet \\\\\\\\\\III fi\\\\\\\\\\ ill! IRWIN R. BARR INVENTOR STRIPPER SHREDDER FOR FRANGIBLE SABOTS DISCLOSURE This is a continuation of copending patent application Ser. No. 606,387 filed Dec.30, 1966 now abandoned.

This invention relates to an improved stripper for projectilelaunching sabots, and more particularly to a stripper which both strips the sabot from the projectile and also shreds or otherwise further comminutes the stripped sabot fragments into desirably smaller particle size in the course of expelling the stripped fragments of the sabot.

In US. Pat. No. 2,81 1,901, a sabot stripping arrangement is disclosed in which a frangible projectile-launching sabot is removed from its finned projectile by longitudinally scoring the sabot about its circumference in the course of passage from a gun barrel, the sabot being aided in removal by the centrifugal force resulting from spin imparted to the sabot while passing through the scoring section. While this is an advantageous sabot removal arrangement, it is sometimes desira ble that the resulting sabot fragments be reduced in size in order to reduce their lethality, particularly inasmuch as their line of flight is not well controlled and as in many instances it is not desirable to have uncontrolled large fragments propelled from the gun, especially in the case of commercial or sport shooting as distinguished from military operations where wide forward dispersal of fragments can not only be tolerated but is sometimes desirable.

It is accordingly a major feature and advantage of this invention to provide an improved stripper arrangement for projectile-launching sabots, which will be termed herein as a stripper-shredder, and in which the sabot is scored and stripped from the projectile while also being shredded or otherwise further comminuted into substantially smaller fragment size, and in some instances to generally powder form, in the course of expelling the removed sabot fragments. The invention is particularly useful in conjunction with sabots which are constructed of resin-bonded glass fibers or other material which is brittle and capable of substantial fragmentation on impact. In the preferred mode of practice of the invention the stripper-shredder also serves as a highly effective muule brake.

Still other objects, features and attendant advantages will become apparent to those skilled in the art from a reading of the following detailed description of a preferred embodiment of the invention, taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a side elevation view in partial section illustrating a strippebshredder employed on a rifle according to the invention,

FIG. 2 is a perspective view in fragmented section illustrating the stripper-shredder of FIG. 1.

FIGS. 3, 4 and 5 are side elevations in partial section showing the sequential operation of the stripper-shredder of FIG. 2.

Referring now in detail to the figures of the drawings, as seen in FIG. 1 a stripper-shredder 21 is secured to the muzzle end of the barrel 13 of a conventional rifle 11. The strippershredder 21 includes a stripper section 25 and shredder section 31. The stripper-shredder is secured to the gun barrel at the entrance end of the stripper section, as through the medium of a threaded section 23 which engages with corresponding threads on the end of the barrel 13. The bore 250 of the stripper section 25 is coaxial with the smooth bore of the rifle barrel l3, and has scoring ridges 25a separated by grooves 25b, the ridges projecting radially inwardly beyond the surface of the smooth bore diameter of the barrel 13, the ridges 25a terminating, however, radially outboard of the projectile fin diameter envelope, and grooves 25b being generally of larger diameter than the diameter of the barrel bore to accommodate the displaced fragments or scored sabot sections during their longitudinal passage through the stripper section. The stripper section 25 serves not only to score the sabot during its passage through the stripper section, but also imparts a spin .to the sabot through the canting of the ridges and grooves. Preferably, the ridges and grooves of the stripper section are progressively canted, or otherwise stated are formed with gained twist, it being preferred that the initial entry zone have zero cant or twist for the cutting ridges and grooves as indicated at 25d, with the ridges and grooves progressing thereafter to a canted angle to the bore axis of increasing cant angle or twist along the length of the stripper section 25 to the exit end of the bore 25:- thereof. Thus, the sabot and projectile are accelerated angularly to a desired spin rate while passing through the stripper section 25, and upon emerging from the bore 25c of the stripper section the scored sabot will tend to fly apart into fragments under the action of the centrifugal force resulting from the spin imparted thereto by the stripper section.

Forward of the exit end of the bore 25c of the stripper section 25 is a radial expansion chamber 27 which is encompassed by a forwardly flared annular side wall 29. The enlarged internal diameter of this chamber 27 enables the scored sabot to separate radially from the projectile as it proceeds toward and through the shredder section 31 which is formed at the forward end of the radial expansion chamber 27.

Shredder section 31 includes a forwardly flared frusto-conical deflector 33 which the sabot fragments impinge while the projectile proceeds through a bore 33b formed in the deflector and which is of a diameter only slightly larger than the projectile. For ease of manufacture, the deflector 33 may take the form of an insert which may be threadedly secured within the forward end of the side wall 29 as by a complementary threaded connection 35. A plurality of longitudinal slots 37 are formed in the periphery of the annular wall 29 about the area of the conical deflection surface 331: of the deflector 33. This conical deflection surface 33a may be and is preferably formed of compound angled surfaces of increasing slope relative to the axis of the bore 33b to thereby provide a plurality of impacts and greater fragmentation or shredding of the sabot parts. The combined action of impacting of the sabot fragments on the conical deflection surface 33a and the passage of the impacted fragments through the narrow slots 37 effects a very substantial reduction of fragment size of the removed sabot. In the case of resin-bonded glass fiber sabots, or sabots formed of other brittle and relatively easily impact frangible material, the sabot will be substantially disintegrated into a relatively fine powder by the combined action of the spin-imparting stripper section 25 and the impact shredder section 31.

In operation, as shown in FIGS. 3-5, a sabot S and projectile P proceed from the barrel 13 of the gun into the stripper section 21, where the sabot is scored and spin is imparted to the sabot and projectile. After emerging from the stripper section 21 into the expansion chamber 27, the sabot S which has now been physically scored or cut about the circumferential surface by the stripper section, partially or fully separates from the projectile under the action of the centrifugal force resulting from the spin imparted by the helical ridges and grooves 25a and 25b. The separated sabot S will then proceed forward in fragmentary form as indicated at SF, and strike the frusto-conical deflector surface 33a, while the projectile P proceeds through the coaxial bore 33b of the deflectorshredder 33. Upon striking the sloped impact surface 33a the sabot will be further broken up into smaller fragments which. depending on angle of impact. may be further impacted forwardly onto the steeper conical surface 33a, being thrown outwardly through the slots 37 by the vector force acting thereon upon impact with the conical surface of the deflectorshredder 33. The projectile P will proceed through the bore 33h while the shredded or powdered sabot fragments SF will be expelled from the slots 37 of the stripper-shredder 21, as indicated at SFS in FIG. 5. It will also be appreciated that the stripper-shredder arrangement serves as an effective muzzle brake by energy absorption from the deflection of sabot fragments from their forward directed path to a more radially directed path in the course of impact shredding.

While the invention has been illustrated and described with respect to a single preferred embodiment, it will be readily apparent that various modifications and improvements may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited by the illustrative embodiment. but only by the scope of the appended claims.

lclaim:

l. A stripper-shredder arrangement for a frangible projectile-launching sabot comprising:

a sabot stripper section having an internally helically fluted sabot stripping and spinning bore surface;

a sabot impact shredder section disposed forward of said stripper section and having a body portion with an inclined sabot impact surface facing and spaced from said stripper section;

a bore formed in said shredder section body portion and being coaxial with said stripping and spinning bore surface; and

said bore formed in said shredder section body portion being smaller in diameter than said stripping and spinning bore surface.

2. A stripper-shredder arrangement according to claim I;

a connecting section formed and connecting between said stripper section and said shredder section;

said connecting section being circumferentially perforated for sabot particle exit from the zone between said stripper section and said shredder section;

said connecting section having an internal cavity formed between said stripper section bore and said shredder body portion bore, and said cavity being larger in internal cross section at its forward end adjacent said impact surface than is the cross section of said shredder body portion bore surface.

3. A stripper-shredder according to claim 1, said inclined impact surface including a plurality of adjoining frusto-conical impact surface zones of succeedingly greater taper angle with respect to the bore axis of said impact element.

4. A stripper-shredder arrangement according to claim 1, and an expansion chamber formed between the exit end of said stripper section bore and said inclined impact surface.

5. A stripper-shredder arrangement according to claim 4;

said expansion chamber being defined by an annular tubular wall connecting between said stripper section and said impact element adjacent the forward end of said outwardly tapered impact surface;

said outwardly tapered impact surface including a frustoconical surface zone; and

said impact element bore being formed coaxial with said frusto-conical surface zone and of a diameter slightly smaller than the small end of said frusto-conical surface zone.

6. A stripper-shredder arrangement according to claim 5, the tubular wall defining saidexpansion chamber having a forwardly-outwardly flared internal annular wall surface configuration along a portion of its length, said particle exit openings being formed in said tubular wall radially outboard of said frusto-conical impact surface.

7. A stripper-shredder arrangement according to Claim 6, and particle exit openings in said shredder section, including longitudinal slots spaced about the annular periphery of said tubular wall and extending along the length of said frustoconical impact surface.

8. A stripper-shredder arrangement according to Claim 7, said impact element being removably threadedly secured within the forward end of said tubular wall.

9. A gun having a barrel with a smooth walled bore therein for guiding a propelled sabot-projectile arrangement being propelled therefrom, said bore being of diameter generally complementary to said sabot and of materially larger diameter than the effective outer diameter of said projectile;

said barrel having a stripper-shredder arrangement formed on the end of said barrel;

said stripper-shredder arrangement comprising: a sabot stripper section having an internally helically fluted sabot stripping and spinning bore surface; and

a sabot impact shredder section disposed forward of said stripper section and having a body portion with an inclined sabot impact surface facing and spaced from said stripper section;

a bore formed in said shredder section body portion and being coaxial with said stripping and spinning bore surface;

said bore formed in said shredder section body portion being smaller to in diameter than said stripping and spinning bore surface;

the entrance end of said stripper section being adjacent to the exit end of said barrel;

said coaxial stripper-shredder bores being coaxial with said barrel bore;

said fluted sabot stripping and spinning bore surface having sabor-scoring ridges extending radially inwardly of said barrel bore. and

said fluted sabot stripping and spinning bore surface having sabot-accommodating grooves extending radially outwardly beyond said barrel bore and being of enlarged width radially beyond the radially innermost cutting edges of said ridges. 

